Coalescing agents are high boiling point solvents (that are slow to evaporate) used to reduce the minimum film formation temperature (MFFT) of paints, inks, other coating compositions and the like. In paint formulations in particular, coalescing agents act as temporary plasticizers to reduce the glass transition temperature (Tg) of the latex below that of the drying temperature to allow for good film formation.
Generally, coalescing agents function by softening the polymer particles in a latex, enabling the formation of a continuous film as the coating cures. It is desirable for the coalescing agent to have low water solubility, which increases its effectiveness, and have good hydrolytic stability.
A typical paint formulation contains between 0.1-10% coalescing agent, which is used to aid in the formation of a continuous film as the paint cures. This market has been historically dominated by Eastman's Texanol™ brand ester alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate). However, as Texanol™ is not compliant with current volatile organic content (VOC) regulations, there is a need for improved coalescing agents or other systems to achieve coalescence in compliance with low VOC regulations. Generally, “low VOC” coalescing agents is understood to mean about 50% less VOC content as compared to regular coalescing agents, for example, Texanol®, which contains 100% VOC content.
It is an object of the present invention to provide an improved and efficient, low VOC coalescent composition which meets present and future VOC regulations for paints and other coatings.